State transition procedure in a wireless network

ABSTRACT

A wireless transmit/receive unit (WTRU) may operate in a first state where the WTRU does not have configured physical channels and discontinuously monitors for pages and a second state where the WTRU has configured uplink physical channels. The WTRU may, in response to a signal, transition to the first state and store an identity and medium access control (MAC) information. The WTRU may reinitiate communication with a network using the stored identity and MAC information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/166,810 filed Jan. 28, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/758,396 filed Feb. 4, 2013, which issued as U.S.Pat. No. 8,644,879 on Feb. 4, 2014, which is a continuation of U.S.patent application Ser. No. 13/425,742 filed Mar. 21, 2012 which issuedas U.S. Pat. No. 8,369,886 on Feb. 5, 2013, which is a continuation ofU.S. patent application Ser. No. 12/346,339 filed Dec. 30, 2008, whichissued as U.S. Pat. No. 8,145,253 on Mar. 27, 2012, which claims thebenefit of U.S. Provisional Application No. 61/038,448 filed Mar. 21,2008, and No. 61/019,150 filed Jan. 4, 2008, the contents of which arehereby incorporated by reference herein.

FIELD OF INVENTION

This application is related to wireless communications.

BACKGROUND

FIG. 1 shows radio resource control (RRC) service states 100 of a ThirdGeneration Partnership Project (3GPP) wireless transmit/receive unit(WTRU) with an enhanced uplink (UL) in a Universal MobileTelecommunications System (UMTS). The WTRU may operate in several statesdepending on user activity. The following states have been defined forUMTS Terrestrial Radio Access (UTRA) radio resource control (RRC)connected mode: IDLE 110, CELL_DCH 120, CELL_FACH 130, URA_PCH 140, andCELL_PCH 150. Other states that the WTRU may transition to include ageneral packet radio service (GPRS) packet transfer mode 160, or aglobal system for mobile communications (GSM) connected mode 170. RRCstate transitions are controlled by the network using radio networkcontroller (RNC) parameters. In general the WTRU does not decide toperform state transitions by itself.

Based on WTRU mobility and activity while in UTRA RRC connected mode(i.e., in the CELL_DCH, CELL_FACH, URA_PCH or CELL_PCH state), the UMTSTerrestrial Radio Access Network (UTRAN) may direct the WTRU totransition between the states CELL_PCH, URA_PCH, CELL_FACH, andCELL_DCH. Communication between the WTRU and the UTRAN, known as userplane communication, is only possible while in the CELL_FACH state orthe CELL_DCH state.

In the CELL_DCH state, a dedicated physical channel is allocated to theWTRU in the UL and the downlink (DL). This corresponds to continuoustransmission and continuous reception in the WTRU, which can bedemanding on user power requirements. The WTRU is known on a cell levelaccording to its current active set. An active set is a set of radiolinks simultaneously involved in a specific communication servicebetween the WTRU and the UTRAN. The WTRU may use dedicated transportchannels, shared transport channels, or a combination of these transportchannels.

A WTRU is in the CELL_FACH state if it has been assigned to use thecommon channels (i.e., forward access channel (FACH), random accesschannel (RACH)). In the CELL_FACH state, no dedicated physical channelis allocated to the WTRU, which allows for better power consumption, atthe expense of a lower UL and DL throughput. Downlink communication inthe CELL_FACH state may be achieved through a shared transport channel(i.e., FACH) mapped to a shared common control physical channel(S-CCPCH). Downlink communication in the CELL_FACH state may also beachieved through a high speed downlink shared channel (HS-DSCH). TheWTRU continuously monitors the FACH channel, carried over the S-CCPCH,or the HS-DSCH, in the DL. Uplink communication in the CELL_FACH stateis achieved through a default common or shared transport channel (i.e.,RACH) mapped to the RACH physical channel (PRACH), which the WTRU mayuse anytime according to the access procedure for that transportchannel. The RACH channel is a contention based channel with a powerramp-up procedure to acquire the channel and to adjust transmit power.The position of the WTRU is known by the UTRAN on a cell level accordingto the cell where the WTRU last performed a cell update.

A characteristics of the CELL_FACH state includes being well-suited forapplications requiring very low uplink throughput. Anothercharacteristic of the CELL_FACH state includes being well-suited forsignaling traffic, such as transmission of CELL UPDATE messages and URAUPDATE messages. Mobility in the CELL_FACH state is handled autonomouslyby the WTRU. The WTRU independently takes measurements and determineswhich cell to camp on. System information (SI), read from the broadcastchannel (BCH), includes setup details for the uplink channel (RACH) andthe downlink channels (FACH and HS-DSCH) to be used in the CELL_FACHstate.

In the CELL_PCH state, no dedicated physical channel is allocated to theWTRU. The WTRU selects a paging channel (PCH), and uses discontinuousreception for monitoring the selected PCH via an associated pageindicator channel (PICH). No UL activity is possible. The position ofthe WTRU is known by the UTRAN on a cell level according to the cellwhere the WTRU last performed a cell update in the CELL_FACH state.

In the URA_PCH state, no dedicated channel is allocated to the WTRU. TheWTRU selects a PCH, and uses discontinuous reception for monitoring theselected PCH via an associated PICH. No UL activity is possible. Thelocation of the WTRU is known on a UTRAN registration area (URA) levelaccording to the URA assigned to the WTRU during the last URA update inthe CELL_FACH state.

Recent 3GPP proposals have identified the possibility of using theenhanced dedicated channel (E-DCH) in the CELL_FACH state, also referredto as Enhanced RACH or E-RACH. The E-DCH was introduced in Release 6 ofthe 3GPP specifications to increase uplink throughput. The enhanceduplink operates on a request/grant principle. WTRUs send an indicationof the requested capacity they require, while the network responds withgrants to the requests. The grants are generated by a Node-B scheduler.Also, hybrid automatic repeat requests (HARQ) are used for physicallayer transmissions. Further, new UL and DL channels were introduced inRelease 6 to support the E-DCH. The new UL physical channels are theE-DCH dedicated physical control channel (E-DPCCH), which is used forcontrol information, and the E-DCH dedicated physical data channel(E-DPDCH), which is used for user data. The new DL physical channels arethe E-DCH absolute grant channel (E-AGCH) and E-DCH relative grantchannel (E-RGCH), which are used for transmission of grants, and theE-DCH HARQ acknowledgement indicator channel (E-HICH), which is used forfast Layer 1 acknowledgement (ACK)/negative acknowledgement (NACK). TheNode-B 220 may issue both absolute grants and relative grants. Grantsare signaled in terms of a power ratio. Each WTRU maintains a servinggrant, which it may convert to a payload size. For Release 6, WTRUmobility is handled by the network through soft handover and the conceptof active sets.

In a pre-Release 8 high speed packet access (HSPA) system, the WTRU maybe signaled to transition between different states. The transitionbetween different states is defined, in pre-Release 8, for systemswithout E-RACH. However, with the introduction of the E-DCH in theCELL_FACH state and Idle mode, there are issues that occur when the WTRUis transitioning between states such as handling of available E-DCHresources, physical channel procedures, and allowing fast and smoothertransitions between different states. Currently, for example, when theWTRU transitions from the CELL_DCH state to the CELL_FACH state, all theresources are released because the previous CELL_FACH state did notsupport E-DCH reception. However, this behavior may not be desirablewhen the WTRU moves from the CELL_DCH state to the CELL_FACH state wherethe cell supports E-DCH transmissions.

Accordingly, a method and apparatus for performing WTRU state transitionwith E-RACH in HSPA systems are desired.

SUMMARY

A method and apparatus for performing state transition of a wirelesstransmit/receive unit (WTRU) which supports enhanced dedicated channel(E-DCH) in the CELL_FACH state is disclosed. Uplink data is transmittedvia an E-DCH while operating in a CELL_FACH state. A radio resourcecontrol (RRC) signal, which includes a reconfiguration message, isreceived while the WTRU is assigned an E-DCH resource. A reconfigurationof the physical channels is performed according to the RRCreconfiguration message. A transition to a CELL_DCH state is performedand uplink data is transmitted in the CELL_DCH state, via the E-DCH.In-synch and out-of-synch parameters are reported.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 shows the RRC states with high speed downlink packet access(HSDPA)/high speed uplink packet access (HSUPA);

FIG. 2 is an exemplary wireless communication system including aplurality of wireless transmit/receive units (WTRUs), a Node-B, a radionetwork controller (RNC), and a core network;

FIG. 3 is a functional block diagram of a WTRU and the Node-B of FIG. 2;

FIG. 4 shows a flow diagram for a transition from the CELL_FACH state tothe CELL_DCH state;

FIG. 5 shows a flow diagram for a transition from the CELL_FACH state tothe CELL_PCH state;

FIG. 6 shows a flow diagram for a transition from the CELL_FACH state tothe URA_PCH state;

FIG. 7 shows a flow diagram for a transition from the CELL_DCH state tothe URA_PCH state;

FIG. 8 shows a flow diagram for a transition from the CELL_PCH state tothe CELL_FACH state;

FIG. 9 shows a flow diagram for a transition from the CELL_DCH state tothe CELL_FACH state, due to a radio link failure;

FIGS. 10A and 10B show a flow diagram for a transition from the CELL_DCHstate to the CELL_FACH state, due to a radio resource control (RRC)reconfiguration message;

FIG. 11 shows a flow diagram for transmitting an RRC message viacontention free access;

FIG. 12 shows a flow diagram of a synchronization procedure; and

FIG. 13 shows a flow diagram of a scrambling code assignment.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of user device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “Node-B” includes but is notlimited to a base station, a site controller, an access point (AP), orany other type of interfacing device capable of operating in a wirelessenvironment.

When referred to hereafter, the terminology “MAC-i”, “MAC-is” or“MAC-i/is” refers to the medium access control (MAC) sub-layer thatsupports E-DCH transmission in the UL for the CELL_DCH state and theCELL_FACH state, and may include but is not limited to “MAC-e”, “MAC-es”or “MAC-e/es” respectively.

The term “E-RACH” and “E-DCH in the CELL_FACH state” is used to describea resource that is used by a WTRU for uplink contention-based access inHSPA+systems. E-RACH may also indicate a combination of a scramblingcode, a channelization code, a timeslot, an access opportunity and asignature sequence, which are associated to uplink contention-basedchannels in future system architecture. E-RACH may also indicate the useof E-DCH in the CELL_FACH state, the CELL_PCH state, the URA_PCH state,or Idle mode.

FIG. 2 shows a wireless communication system 200 including a pluralityof WTRUs 210, a Node-B 220, an RNC 230, and a core network 240. As shownin FIG. 2, the WTRUs 210 are in communication with the Node-B 220, whichis in communication with the RNC 230, which is in communication with thecore network 240. Although three WTRUs 210, one Node-B 220, and one RNC230 are shown in FIG. 2, it should be noted that any combination ofwireless and wired devices may be included in the wireless communicationsystem 200.

FIG. 3 is a functional block diagram 300 of a WTRU 210 and the Node-B220 of the wireless communication system 200 of FIG. 2. As shown in FIG.3, the WTRU 210 is in communication with the Node-B 220 and the WTRU 210is configured to perform a method of state transition when the WTRU 210supports E-DCH in the CELL_FACH state.

In addition to the components that may be found in a typical WTRU, theWTRU 210 includes a processor 215, a receiver 216, a transmitter 217,and an antenna 218. The processor 215 is configured to perform a methodof state transition when the WTRU 210 supports E-DCH in the CELL_FACHstate. The receiver 216 and the transmitter 217 are in communicationwith the processor 215. The antenna 218 is in communication with boththe receiver 216 and the transmitter 217 to facilitate the transmissionand reception of wireless data. Although one WTRU 210 antenna 218 isshown in FIG. 3, it should be noted that more than one antenna may beincluded in the WTRU 210.

In addition to the components that may be found in a typical Node-B, theNode-B 220 includes a processor 225, a receiver 226, a transmitter 227,and an antenna 228. The processor 225 is configured to perform a methodof state transition when a cell supports E-DCH in the CELL_FACH state.The receiver 226 and the transmitter 227 are in communication with theprocessor 225. The antenna 228 is in communication with both thereceiver 226 and the transmitter 227 to facilitate the transmission andreception of wireless data. Although one antenna 228 is shown in FIG. 3,it should be noted that more than one antenna may be included in theNode-B 220.

FIG. 4 shows a flow diagram for a transition from the CELL_FACH state tothe CELL_DCH state. The WTRU 210 may be configured to operate in theCELL_FACH state (401). The WTRU 210 receives a reconfiguration messageindicating a reconfiguration of the WTRU 210 to the CELL_DCH state(402). The reconfiguration message may also indicate a reconfigurationof physical channel parameters. The reconfiguration message may besignaled, for example, via a cell update confirm message or throughreception of an RRC reconfiguration message. The WTRU 210 determineswhether it has an ongoing E-DCH procedure in the CELL_FACH state (403).If the WTRU 210 has an ongoing E-DCH procedure in the CELL_FACH state,E-DCH resources will already have been assigned to the WTRU 210. If theWTRU 210 has an ongoing E-DCH procedure, reconfigure the physicalchannel parameters based on the reconfiguration message (407). The WTRU210 transitions to the CELL_DCH state (408). If an E-DCH procedure isongoing, the WTRU 210 may be considered in-synch (i.e. insynchronization with the DL physical channels established during theE-DCH procedure in the CELL_FACH state) at the time of the statetransition, because the WTRU 210 has already established an RL with theNode-B 220 at the time of the state transition. Therefore, to avoidadditional delays associated with synchronization upon state transitionto the CELL_DCH state, the WTRU 210 may immediately transition to theCELL_DCH state without performing synchronization procedure A.Synchronization procedure A, as defined in 3GPP TS25.214, is asynchronization procedure that may be performed when no prior RL existedbefore the state transition. Upon transition to the CELL_DCH state, theWTRU 210 transmits UL data via the E-DCH (409). The WTRU 210 may alsotransmit UL control information via the E-DCH in the CELL_DCH state.Optionally, the WTRU 210 may wait to resume UL transmissions until anactivation time signaled by the network 240, or it may wait and transmitat the UL E-DCH frame boundary. The WTRU 210 may monitor radio linksynchronization criteria as required in the CELL_DCH state, as definedin 3GPP TS 25.331. More specifically, the WTRU 210 may immediately moveto phase 2 of the synchronization procedure A, where the WTRU 210 mayreport both in-synch and out-of-synch parameters (410). The WTRU 210 mayreport the parameters to a higher layer radio link monitoring function.The synchronization criteria may be monitored immediately after thestate transition, or it may be performed after the DL physical channelsare established.

If there is no ongoing E-DCH transmission in the CELL_FACH state,reconfigure the physical channel parameters (404), transition to theCELL_DCH state (405), perform Synchronization Procedure A (406), andtransmit UL data (409). The WTRU 210 receives an enhanced radio networktemporary identifier (E-RNTI) assignment from the network 240 and mayset an E_RNTI variable based on the assignment, which is used to reducedelays associated with UL data transmission. The WTRU 210 may beconfigured to keep the variable E_RNTI used in the CELL_FACH state.Optionally, if a new E-RNTI assignment is received, the WTRU 210 mayreconfigure the variable E_RNTI to the assigned E-RNTI value. The WTRU210 may reset the medium access control (MAC)-i/is entity. The reset maybe performed autonomously upon the state transition. Optionally, thereset may be explicitly indicated by an RRC reconfiguration message viaa MAC-i/is reset indicator.

Upon transitioning to the CELL_DCH state, the WTRU 210 may be configuredto set an initial UL transmit power level for transmission in theCELL_DCH state. The WTRU 210 may set the initial UL transmit power tothe same UL transmit power used by the WTRU 210 prior to transitioningto the CELL_DCH state. Alternatively, the WTRU 210 may obtain theinitial UL transmit power from a power offset, ΔdB, which is configuredby the network 240. The WTRU 210 may apply the power offset to the powerused by the WTRU 210 in the CELL_FACH state prior to transitioning tothe CELL_DCH state.

Alternatively, when transitioning to the CELL_DCH state, the WTRU 210may be configured to perform Synchronization Procedure B only.Synchronization Procedure B, as defined in 3GPP TS 25.214, is asynchronization procedure that may be performed when one or more RLs areadded to the active set and at least one of the RLs that existed priorto the state transition still exist after the state transition. Upontransitioning to the CELL_DCH state, the WTRU 210 may be configured toset an initial UL transmit power for transmission in the CELL_DCH state.The WTRU 210 may set the initial UL transmit power to the same ULtransmit power used by the WTRU 210 prior to transitioning to theCELL_DCH state. Alternatively, the WTRU 210 may obtain the initial ULtransmit power from a power offset, ΔdB, which is configured by thenetwork 240. The WTRU 210 may apply the power offset to the power usedby the WTRU 210 in the CELL_FACH state prior to transitioning to theCELL_DCH state.

Alternatively, the WTRU 210 may be configured to perform SynchronizationProcedure A only, and the initial UL transmit power may be configured tobe the same UL transmit power used by the WTRU 210 in the CELL_FACHstate prior to transitioning to the CELL_DCH state. Alternatively, theWTRU 210 may obtain the initial UL transmit power from a power offset,MB, which is configured by the network 240. The WTRU 210 may apply thepower offset to the power used by the WTRU 210 in the CELL_FACH stateprior to transitioning to the CELL_DCH state.

The WTRU 210 may be configured to use a serving grant, which may beconfigured to be below a certain value during the synchronizationprocedure, if a synchronization procedure is executed. Alternatively, nosynchronization procedure is executed, but the serving grant of the WTRU210 is configured to be below a certain value during a pre-determinedperiod of time after physical reconfiguration. The maximum value of theserving grant in either case may be signaled by higher layers, forexample, signaled by the RRC through system information blocks (SIB)s,or signaled in a reconfiguration message. Alternatively, the Node-B 220may refrain from issuing a serving grant above the maximum value duringthe pre-determined period of time, which may be signaled by higherlayers.

A WTRU 210 may be in one of four UL transmission modes in the CELL_FACHstate when it receives a state transition message. The UL transmissionmodes may be defined as follows: a) the WTRU 210 is not transmittingE-DCH transmissions; b) the WTRU 210 is transmitting PRACH preambles; c)the WTRU 210 is performing a collision resolution; and d) the WTRU 210is transmitting E-DCH transmissions, following a collision resolution.The WTRU 210 behavior may be specified for each of these modes. Inaddition, the WTRU 210 behavior may be specified if the network 240requests an immediate transition (i.e. an activation time=“now”), oroptionally if the network 240 requests a transition at a futureactivation time.

When the WTRU 210 is in the mode of not transmitting E-DCH transmissionsand a state transition message is received, the WTRU 210 may beconfigured to perform the actions as defined in 3GPP release 7 andearlier. If a future activation time is specified, the WTRU 210 mayoptionally prevent any RACH or E-RACH access attempts until the futureactivation time.

When the WTRU 210 is in the mode of sending PRACH preambles and a statetransition message is received, the WTRU 210 may be configured toterminate its E-DCH transmission attempt. If a future activation time isspecified, the WTRU 210 may optionally make a decision whether or not tocontinue with the E-RACH access based on a combination of any of thefollowing: logical channel, amount of data to transmit, and time untilstate transition is to take effect. Alternatively, the WTRU 210 maycontinue with E-DCH transmission if after transmitting the lastpreamble, prior to receiving the reconfiguration message, it receives apositive acknowledgment on the acquisition indicator channel (AICH) or aresource assignment on the E-DCH AICH (E-AICH). The WTRU 210 may wait aperiod of time (TP-a) prior to deciding to terminate E-RACH access.TP-a, as defined in 3GPP TS25.214, is a period of time from thetransmission of a preamble to the time when the WTRU 210 expects toreceive an AICH response. If the WTRU 210 does not receive either aresource assignment or an acknowledgment, the WTRU 210 may not continueE-RACH access.

When a WTRU 210 is in the mode of performing a collision resolution anda state transition message is received, the WTRU 210 may be configuredto terminate its E-RACH access attempt. At the time of the statetransition, the WTRU 210 may flush the HARQ buffers, or optionally,perform a MAC-i/is reset. If a future activation time is specified, theWTRU 210 may optionally make a decision whether or not to continue withthe E-DCH transmission based on a combination of any of the following:logical channel, amount of data to transmit, and time until statetransition is to take effect.

When the WTRU 210 is in the mode of transmitting an E-DCH transmission,after collision resolution, and a state transition message is received,the WTRU 210 may be configured based on a specified activation time.

When the activation time is set to “now”, the WTRU 210 may be performingongoing HARQ processes. The WTRU 210 may be configured to completeretransmissions for the ongoing HARQ processes. The WTRU 210 may retainthe E-DCH resource, including an UL scrambling code, until allretransmissions have been completed. The WTRU 210 may refrain frominitiating any new HARQ processes on the E-DCH resource and may refrainfrom transmitting any new data. The transition to the CELL_DCH state maybe made either after the last protocol data unit (PDU) is transmittedsuccessfully, or after all retransmissions have been attempted. The WTRU210 may then signal the network 240 that it is capable of transitioningto the new E-DCH resource. The signal may be transmitted by a layer 1 orlayer 2 message. Before ordering a state transition, the network 240waits to receive this signal or waits until the E-DCH resources arereleased from the network 240, for example, via explicit signaling, orbased on the expiration of a timer. Optionally, the WTRU 210 does notinform the network 240 that it is capable of transitioning to a newstate, but rather transitions as soon as it completes the HARQtransmissions.

When a future activation time is specified, the WTRU 210 may beconfigured to continue using the E-DCH resource until that activationtime is reached. The WTRU 210 may prevent all new transmissions up untilthe activation time, or optionally, it may mark a window before theactivation time as unavailable for starting new transmissions. The sizeof the window may be specified, configured by the network 240, ordetermined by the WTRU 210 as a function of the maximum time it wouldtake to transmit a new PDU, including maximum retransmissions. Forexample, if the maximum time to complete a transmission of a new PDU isgreater than the time remaining prior to the expiration of theactivation time, the WTRU 210 may not allow the new transmission. TheWTRU 210 may also base the decision whether or not to start a newtransmission on any combination of the following: the logical channel,the amount of data to transmit, and the time until state transition isto take effect.

At the time of the state transition, the WTRU 210 may be configured toflush all HARQ buffers for PDUs that are not involved in ongoing HARQprocesses, but may continue active HARQ process transmissions. Theactive HARQ processes may be transmitted using an interim E-DCHconfiguration, and may prevent any new transmissions until the activeHARQ processes terminate. Alternatively, if the HARQ processconfiguration parameters are the same as for the E-DCH HARQ processes,the WTRU 210 may continue transmission of the HARQ processes in theCELL_DCH state seamlessly without having to perform a MAC-i/is reset orflush the HARQ buffers.

For the DL, the WTRU 210 may configure the new DL channels as specifiedin the state transition message. For the UL, the WTRU 210 may onlychange the scrambling code. The WTRU 210 may continue to use all otherE-DCH configuration parameters associated to the E-RACH resource. Whenthe last PDU has been either acknowledged or retransmitted the maximumnumber of times, the WTRU 210 may transition to the new ULconfiguration. The WTRU 210 may need to signal the network 240 that ishas transitioned to the new UL E-DCH resource. The signal may betransmitted by a layer 1 or layer 2 message.

Alternatively, the WTRU 210 may be configured to perform the statetransition at a given activation time. The given activation time can beset to “now” or any value determined by the network 240.

At the time of the transition, the WTRU 210 may perform one or acombination of the following: flush the HARQ buffers; only flush theHARQ buffers if the HARQ configuration (i.e. the number of HARQprocesses, the HARQ memory allocation, or the transmission time interval(TTI) value) changes; reset the MAC-ids entity or alternatively refrainfrom resetting the MAC-i/is entity. The transmission sequence number(TSN) may be maintained as long as the MAC-i/is entity in the servingRNC (S-RNC) remains unchanged. Optionally, the reset of the MAC-i/isentity may only be performed if there is an explicit MAC-i/is resetindicator in the RRC reconfiguration message.

FIG. 5 shows a flow diagram for a transition from the CELL_FACH state tothe CELL_PCH state. The WTRU 210 may be configured to operate in theCELL_FACH state (501). The WTRU 210 determines if there is an ongoingE-DCH procedure (502). The E-DCH procedure may include one of E-DCHtransmission procedures or E-DCH reception procedures, or bothprocedures. E-DCH transmission procedures may include E-DPDCH, DPCCH, orE-DPCCH transmission. E-DCH reception may include E-AGCH, E-HICH, orE-RGCH reception. If there is an ongoing E-DCH procedure, terminate anyE-DCH transmission procedures and reception procedures which areoccurring (503). The WTRU 210 releases HARQ resources (504), resets theMAC-i/is entity (505), and transitions to the CELL_PCH state (506). Ifthere is no ongoing E-DCH procedure, the WTRU 210 releases HARQresources (504), resets the MAC-i/is entity (505), and transitions tothe CELL_PCH state (506).

FIG. 6 shows a flow diagram for a transition from the CELL_FACH state tothe URA_PCH state. The WTRU 210 may be configured to operate in theCELL_FACH state (601). The WTRU 210 determines if there is an ongoingE-DCH procedure (602). The E-DCH procedure may include one of E-DCHtransmission procedures or E-DCH reception procedures, or bothprocedures. E-DCH transmission procedures may include E-DPDCH, DPCCH, orE-DPCCH transmission. E-DCH reception procedures may include E-AGCH,E-HICH, or E-RGCH reception. If there is an ongoing E-DCH procedure,terminate any E-DCH transmission procedures and reception procedureswhich are occurring (603). The WTRU 210 releases HARQ resources (604).Alternatively, the WTRU 210 may be configured to maintain HARQresources. The WTRU 210 resets the MAC-i/is entity (605). Optionally,the WTRU 210 may be configured to maintain the MAC-i/is entity. The WTRU210 transitions to the URA_PCH state (606), and clears the E_RNTIvariable (607). Alternatively, the WTRU 210 may maintain the variableE_RNTI. Alternatively, the WTRU 210 may receive a primary E-RNTI valueand a secondary E-RNTI value from the Node B 220, and may maintain theprimary E-RNTI value only, while clearing the secondary E-RNTI value. Ifthere is no ongoing E-DCH procedure, the WTRU 210 releases HARQresources (604), resets the MAC-i/is entity (605), transitions to theURA_PCH state (606), and clears the E_RNTI variable (607).

FIG. 7 shows a flow diagram for a transition from the CELL_DCH state tothe URA_PCH state. The WTRU 210 may be configured to operate in theCELL_DCH state (701). The WTRU 210 determines if there is an ongoingE-DCH procedure (702). The E-DCH procedure may include one of E-DCHtransmission procedures or E-DCH reception procedures, or bothprocedures. E-DCH transmission procedures may include E-DPDCH, DPCCH, orE-DPCCH transmission. E-DCH reception procedures may include E-AGCH,E-HICH, or E-RGCH reception. If there is an ongoing E-DCH procedure,terminate any E-DCH transmission procedures and reception procedureswhich are occurring (703). The WTRU 210 releases HARQ resources (704).Alternatively, the WTRU 210 may be configured to maintain HARQresources. The WTRU 210 resets the MAC-i/is entity (705). Optionally,the WTRU 210 may be configured to maintain the MAC-i/is entity. The WTRU210 transitions to the URA_PCH state (706) and clears the E_RNTIvariable (707). Alternatively, the WTRU 210 may be configured tomaintain the variable E_RNTI. Alternatively, the WTRU 210 may beconfigured to receive a primary E-RNTI value and a secondary E-RNTIvalue from the Node B 220, and may maintain the primary E-RNTI valueonly, while clearing the secondary E-RNTI value. If there is no ongoingE-DCH procedure, the WTRU 210 releases HARQ resources (704), resets theMAC-i/is entity (705), transitions to the URA_PCH state (706), andclears the E_RNTI variable (707).

Allowing the E_RNTI variable, MAC-i/is entity, and HARQ resources to bemaintained while in the CELL_PCH state may allow the WTRU 210 to performa faster transition to the CELL_FACH state in the case of ULtransmission of messages other than the common control channel (CCCH).

FIG. 8 shows a flow diagram for a transition from the CELL_PCH state tothe CELL_FACH state. The WTRU 210 may be configured to operate in theCELL_PCH state (801). The WTRU 210 determines whether there is UL datato transmit (802). If there is no UL data to transmit, the WTRU 210remains in the CELL_PCH state, unless informed otherwise by the network240. If there is UL data to transmit, determine if the WTRU 210 supportsE-DCH transmission in the CELL_FACH state (803). If the WTRU 210 doesnot support E-DCH transmission in the CELL_FACH state, then the WTRU 210performs a cell update via the legacy RACH as defined in 3GPP TS25.331,pre-release 8 (804). If the WTRU 210 supports E-DCH transmission in theCELL_FACH state, then the WTRU 210 determines if the E_RNTI variable isset (805). The WTRU 210 receives an E-RNTI assignment from the network240 and may set an E_RNTI variable based on the assignment, which isused to reduce delays associated with UL data transmission. If theE_RNTI variable is set, then transition to the CELL_FACH state (806).The WTRU 210 acquires a shared E-DCH resource in the CELL_FACH state forUL transmission (807), and transmits UL data via the E-DCH (808). Delaysassociated with UL transmission are reduced since the WTRU 210transitions to the CELL_FACH state and may immediately initiate UL datatransmission, without having to start a cell update procedure.Optionally, if the variable E_RNTI was cleared while the WTRU 210 was inthe CELL_FACH state and the WTRU 210 has a cell RNTI (C-RNTI) and anHS-DSCH RNTI (H-RNTI), the WTRU 210 may be configured to use the E-RACHto start UL transmission using a common or randomly chosen E-RNTI value.If the WTRU 210 does not have an E_RNTI variable set, then transition tothe CELL_FACH state (809) and perform a cell update via the E-DCH (810)before transmitting UL data (808).

The WTRU 210 may be configured to receive a preamble and acquisitionindicators over the AICH from the Node-B 220. The WTRU 210 may beconfigured to set up the HS-DPCCH and to send channel quality indicator(CQI) feedback to the Node-B 220. The WTRU 210 may be configured to sendthe CQI feedback more frequently, for example, at consecutive TTIs, atthe beginning of the transmission, or at a configured frequency asspecified in system information blocks (SIB), or at a cyclepredetermined in the WTRU 210. The WTRU 210 may be configured to includea scheduling information (SI) field in its E-DCH transmission andoptionally in subsequent E-DCH transmissions.

The WTRU 210 may be configured to transition from the CELL_DCH state tothe CELL_FACH state due to a radio link (RL) failure, where the WTRU 210may perform a cell update procedure. The WTRU 210 may also be configuredto transition from the CELL_DCH state to the CELL_FACH state due to anRRC reconfiguration message.

FIG. 9 shows a flow diagram for a transition from the CELL_DCH state tothe CELL_FACH state. The WTRU 210 may be configured to operate in theCELL_DCH state (901). The WTRU 210 determines if an RL failure occurs(902). If an RL failure does not occur, the WTRU 210 remains in theCELL_DCH state, unless otherwise configured by an RRC message. If an RLfailure occurs, the WTRU 210 determines if there are any E-DCHtransmission procedures or E-DCH reception procedures occurring (903).E-DCH transmission may include E-DPDCH, DPCCH, or E-DPCCH transmissions.E-DCH reception may include E-AGCH, E-HICH, or E-RGCH reception. Ifthere are E-DCH transmission procedures or E-DCH reception proceduresongoing, terminate those procedures (904). The WTRU 210 clears thevariable E_RNTI (905). If UL dual cell or multi-cell operation isconfigured, the WTRU 210 may clear the E-RNTI values that are associatedwith a secondary cell or cells and may also terminate E-DCH transmissionand E-DCH reception procedures associated with the secondary cell orcells. Optionally, the WTRU 210 may be configured to clear the variableE_RNTI only if the cell the WTRU 210 is reselecting to after the RLfailure is different than the cell serving the E-DCH at the time of theRL failure. The WTRU 210 resets the MAC-i/is entity (906), transitionsto the CELL_FACH state (908), and transmits a cell update message (909).If there is no E-DCH transmission or E-DCH reception proceduresoccurring, then clear the variable E_RNTI (907) and transition to theCELL_FACH state (908).

The WTRU 210 may be configured to perform an E-RACH access procedure inthe CELL_FACH state to transmit the cell update message. As part of theE-RACH access procedure, the WTRU 210 may select a new configuration forone or more of the E-DPDCH, E-DPCCH, E-AGCH, E-HICH, or E-RGCH as partof the E-DCH RACH access procedure. Optionally, the WTRU 210 mayreconfigure the E-DPDCH and E-DPCCH according to the new configurationthat was selected as part of the E-RACH access procedure. Optionally,the WTRU 210 may also reconfigure the E-AGCH, E-HICH, and E-RGCHaccording to the new configuration that was selected as part of theE-RACH access procedure.

The WTRU 210 may be configured to transmit data blocks in intervalscalled transmission time intervals (TTIs). When initiating transmissionover the E-DCH in the CELL_FACH state to initiate a cell updateprocedure due to an RL failure, the WTRU 210 may be configured to use a10 ms TTI if the WTRU 210 was transmitting over the E-DCH using a 2 msTTI before the RL failure. Alternatively, the WTRU 210 may transmit overthe RACH as specified in 3GPP pre-Release 6.

FIGS. 10A and 10B show a flow diagram for a transition from the CELL_DCHstate to the CELL_FACH state. The WTRU 210 may be configured to operatein the CELL_DCH state configured with an E-DCH resource (1001). The WTRU210 receives an RRC reconfiguration message to change to the CELL_FACHstate (1002) and determines if there are E-DCH transmission proceduresoccurring (1003). E-DCH transmission may include E-DPDCH or E-DPCCHtransmission. If there are E-DCH transmission procedures occurring, thetransmission procedures are terminated (1004). The WTRU 210 determinesif there are E-DCH reception procedures occurring (1005). E-DCHreception may include E-AGCH, E-HICH, or E-RGCH reception. If there areE-DCH reception procedures occurring, terminate the reception procedures(1006). The WTRU 210 determines if the cell supports E-DCH in theCELL_FACH state (1007). If the cell does not support E-DCH in theCELL_FACH state, then operate in the CELL_FACH state without E-DCH(1009). If the cell supports E-DCH in the CELL_FACH state, the WTRU 210resets the MAC-i/is entity (1008). The reset may be performed each timethe state transition occurs. Alternatively, the reset may be performedvia explicit signaling from the RRC message via a MAC-i/is resetindicator. The WTRU 210 determines if a new E-RNTI assignment isreceived (1010). If a new E-RNTI assignment is received from the Node B220, then operate in the CELL_FACH state with the new E-RNTI valueassigned (1012). If a new E-RNTI assignment is not received, then usethe current E-RNTI value. The WTRU 210 transitions to the CELL_FACHstate (1013). Optionally, the WTRU 210 may be configured to flush theHARQ buffers.

The WTRU 210 may be provided contention free access over the E-RACH, totransmit an UL RRC reconfiguration complete message to the network 240,to confirm that a state transition was successful.

FIG. 11 shows a method for contention free access for transmitting anRRC message. The WTRU 210 may be configured to receive an RRCreconfiguration message to change to a new state such as the CELL_FACHstate, the CELL_PCH state, or the URA_PCH state, wherein the messagecontains a contention free E-DCH resource (1101). The WTRU 210transitions to the new state (1102) and transmits an RRC reconfigurationcomplete message to the network 240 using the contention free E-DCHresource (1103). The transmitted message may also be an RRCreconfiguration failure message. Optionally, the WTRU 210 may beconfigured to receive UL physical channel resources from a pool ofbroadcasted resources to be used for the contention free accesstransmission. The WTRU 210 may use a preamble signature sequenceprovided in the RRC reconfiguration message to initiate a preamble powerramping cycle to establish a pre-determined transmission power. The WTRU210 may wait to receive an AICH message, then immediately transmit theRRC reconfiguration complete message, without having to perform acontention resolution phase.

Alternatively, the WTRU 210 may be configured to transmit the RRCreconfiguration complete message as soon as the pre-determined power isestablished without waiting for the AICH message. The power level usedby the WTRU 210 may be the same power that the WTRU 210 was using priorto transitioning to the CELL_FACH state. Alternatively, the WTRU 210 maybe configured to receive the initial power level, or a power offset,from the network 240 to start using upon transmission, relative to thepower of the last transmission. Alternatively, the initial power levelmay be a pre-configured power level.

The WTRU 210 may be configured to receive a signal from the network 240,containing an explicit E-DCH resource, either in the form of an index toa set of broadcasted resources or a dedicated resource allocation withexplicit parameters as part of an existing or new RRC message. The WTRU210 may then be configured to initiate a synchronization procedure.

FIG. 12 shows a flow diagram of a synchronization procedure. The WTRU210 may be configured to transmit on the DPCCH at a predeterminedinitial power level (1201). The power level may be received from thenetwork 240 as an absolute value or as an offset with respect to thepower of the previous transmission. The WTRU 210 monitors the fractionaldedicated physical channel (F-DPCH) for transmit power control (TPC)commands (1202). The WTRU 210 determines whether TPC commands indicatingthat the power level should be increased (i.e., “up” commands) arereceived (1203). If up TPC commands are received, the WTRU 210 increasespower on the DPCCH by a pre-determined amount (1204). If up TPC commandsare not received, the WTRU 210 continues to monitor the F-DPCH for TPCcommands. The WTRU 210 determines whether TPC commands indicating properpower level (i.e., “down” commands) are received on the F-DPCH (1205).If down TPC commands are received, the WTRU 210 transmits a message(1206). If down TPC commands are not received, the WTRU 210 increasesthe power on the DPCCH by a fixed amount (1204) and determines whether adown TPC command is received (1205).

Optionally, a longer synchronization period may be used to helpstabilize the power control loop. The duration of the synchronizationperiod may be pre-configured, signaled by the network 240 using RRCdedicated signaling, or broadcasted. Optionally, SynchronizationProcedure A may also be used.

The E-DCH in the CELL_FACH state or Idle mode may also be used where thenetwork 240 is aware that the WTRU 210 has to respond with an ULtransmission in the CELL_FACH state.

FIG. 13 shows a flow diagram for a scrambling code assignment. The WTRU210 may be configured to transmit an RRC message over the CCCH (1301).The WTRU 210 receives a scrambling code assignment from the network 240(1302). The scrambling code assignment may be received, for example, viaan RRC confirmation message or an RRC setup message. The WTRU 210configures the physical layer with the scrambling code for ULtransmissions (1303) and determines whether a message is received fromthe network 240 indicating a scrambling code reconfiguration (1304). Ifa message is received indicating a new scrambling code configuration,the WTRU 210 configures the physical layer with the new scrambling codefor UL transmissions (1305). If no scrambling code reconfigurationmessage is received, the WTRU 210 continues with the currentlyconfigured scrambling code until a scrambling code reconfigurationmessage is received.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) unit, anorganic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising: a transceiver; a processor; and the processor is configuredto transition from a first state to a second state, wherein in the firststate the WTRU does not have configured physical channels anddiscontinuously monitors for pages and in the second state the WTRU hasconfigured uplink physical channels; the transceiver is configured toreceive a signal from a network to transition to the first state; andthe processor is configured, in response to the signal, to transition tothe first state, and to store an identity and medium access control(MAC) information, wherein the stored identity and MAC information isutilized to reinitiate communication with the network.
 2. The WTRU ofclaim 1, wherein the MAC information is MAC configuration information.3. The WTRU of claim 1, wherein the identity is an E-RNTI.
 4. The WTRUof claim 1, wherein the first state is a URA_PCH state and the secondstate is a CELL_FACH state.
 5. A method performed by a wirelesstransmit/receive unit (WTRU), the method comprising: transitioning, bythe WTRU, from a first state to a second state, wherein in the firststate the WTRU does not have configured physical channels anddiscontinuously monitors for pages and in the second state the WTRU hasconfigured uplink physical channels; receiving, by the WTRU, a signalfrom a network to transition to the first state; and transitioning, bythe WTRU in response to the signal, to the first state, and to store anidentity and medium access control (MAC) information, wherein the storedidentity and MAC information is utilized to reinitiate communicationwith the network.
 6. The method of claim 5, wherein the MAC informationis MAC configuration information.
 7. The method of claim 5, wherein theidentity is an E-RNTI.
 8. The method of claim 5, wherein the first stateis a URA_PCH state and the second state is a CELL_FACH state.